This invention relates to a method for preventing and/or treating vaginal atrophy, hypogonadism, diminished libido and menopause in susceptible warm-blooded animals including humans involving administration of dehydroepiandrosterone (DHEA), dehydroepiandrosterone-sulfate (DHEA-S) or compounds converted in vivo to either and to pharmaceutical products for delivery of active ingredient(s) useful to the invention.
Primates are unique in having adrenals that secrete large amounts of the precursor steroid dehydroepiandrosterone (DHEA) and especially DHEA-sulfate (DHEA-S), which are converted into androstenedione (.DELTA.4-dione) or androstene-diol (.DELTA..sup.5 -diol) and then into potent androgens and estrogens in peripheral tissues (Adams, Mol. Cell. Endocrinol. 41: 1-17, 1985; Labrie et al., in Important Advances in Oncology (de Vita S, Hellman S, Rosenberg SA, eds), JB Lippincott, Philadelphia Pa., pp 193-200, 1985). DHEA-S, the major steroid present in blood of both men and women is converted into DHEA and .DELTA.5-diol in peripheral tissues, thus maintaining a close correlation between the concentration of these three steroids in the blood (Adams, Mol. Cell. Endocrinol. 41: 1-17, 1985). Depending upon the relative activities of 17.beta.-hydroxysteroid dehydrogenase (17.beta.-HSD), aromatase and 5.alpha.-reductase, DHEA or its derivatives will be preferentially converted into androgens and/or estrogens.
The low serum values of DHEA and DHEA-S found at birth persist up to six years of age. Usually, during the 7th year of age, serum levels of these two steroids increase and continue to rise until age 16 in both boys and girls (Orentreich et al., J. Clin. Endocr. Metab. 59: 551-555, 1984). A further increase is then seen in males, who typically reach maximal levels between 20 and 24 years of age. In women, there is usually no further increase after 16 years. DHEA and DHEA-S decrease with aging in both men and women (Vermeulen and Verdoreck, J. Steroid Biochem. 7: 1-10, 1976; Vermeulen et al., J. Clin. Endocr. Metab. 54: 187-191, 1982). In fact, at 70 years of age, serum DHEA-S levels are at approximately 20% of their peak values while they decrease by up to 95% by the age of 85 to 90 years (Migeon et al., J. Clin. Endocr. Metab. 17: 1051-1062, 1957). The 70% to 95% reduction in the formation of DHEA-S by the adrenals during aging results in a dramatic reduction in the formation of androgens and estrogens in peripheral target tissues, thus resulting in a marked decrease in the biochemical and cellular functions induced by sex steroids.
In addition to the decrease in DHEA-S formation, in men, a progressive decrease in the concentration of testosterone in the spermatic vein (Giusti et al., Exp. Gerontol. 10: 241-245, 1975) as well as in plasma (Lewis et al., Acta Endocrinol. 82: 444-448, 1976; Zumoff et al., J. Clin. Endocr.Metab. 54: 534-538, 1982) has been observed after the age of 60-70 years. Such data, however, have been the subject of controversy (Nieschlag et al., J. Clin. Endocr. Metab. 55: 676-681, 1982). In postmenopausal women, serum testosterone levels are lower than during reproductive life (Forest MG, Physiological changes in circulating androgens, in Androgens in Childhood (Forest MG, ed), Karger Basel, p. 104-129, 1989).
The skin is an important site of sex steroid formation and its function is known to be regulated by sex steroids. Sex steroids can act directly in the skin or may stimulate growth hormone and prolactin secretion by the anterior pituitary gland. Skin atrophy is in fact known to occur in growth hormone deficiency, probably through a secondary decrease in insulin-like growth factor (IGF-1) secretion. Serum growth hormone (GH) and insulin-like growth factor (IGF-1) levels are known to be reduced in aging men and women.
Plasma DHEA-S concentration has been suggested as a predictor of osteoporosis (Nordin et al., J. Clin. Endocr. Metab. 60: 651-657, 1985; Deutsch et al., Int. J. Gynecol. Obstet. 25: 217-220, 1987). Serum DHEA has in fact been found to be significantly lower in osteoporotic compared to normal subjects (Nordin et al., J. Clin. Endocr. Metab. 60: 651-657, 1985). Low tissue .DELTA.4-dione is also likely to accompany low DHEA-S levels. Since .DELTA.4dione is the precursor of estrone which is a main source of estradiol in postmenopausal women (Marshall et al., Clin. Endocrinol. 9: 407, 1978), such secondary low levels of estrogens are likely to be involved in osteoporosis (Nordin et al., Lancet 2: 277, 1981).
As another mechanism, low serum DHEA-S levels resulting in low formation of androgens in peripheral tissues could also result in low bone formation, a characteristic of postmenopausal osteoporosis (Meunier et al., in Histological heterogeneity of apparently idiopathic osteoporosis and treatment (DeLuca HF, Frost HM, Jee WSS, Johnston Jr CC, Parfitt AM, eds), University Park Press, Baltimore, p. 293). In fact, Deutsch et al. (Int. J. Gynecol. Obstet. 25: 217-222, 1987) have found a significant correlation between serum DHEA-S and androstenedione levels and osteoporosis in late postmenopausal women while no correlation was found between serum estrogens and bone density, thus suggesting a major importance of androgens in postmenopausal bone loss.
Studies in animals have shown that androgen deficiency leads to osteopenia while testosterone administration increases the overall quantity of bone (Silverberg and Silverberg, 1971; See Finkelstein et al., Ann. Int. Med. 106: 354-361, 1987). Orchiectomy in rats can cause osteoporosis detectable within 2 months (Winks and Felts, Calcif. Tissue. Res. 32: 77-82, 1980; Verhas et al., Calcif. Tissue Res. 39. 74-77, 1986).
As mentioned earlier, adrenal androgen levels have been found to be reduced in osteoporosis (Nordin et al., J. Clin. Endocr. Metab. 60: 651, 1985). Moreover, elevated androgens in postmenopausal women have been shown to protect against accelerated bone loss (Deutsch et al., Int. J. Gynecol. Obstet. 25: 217-222, 1987; Aloia et al., Arch. Int. Med. 143: 1700-1704, 1983). In agreement with such a role of androgens, urinary levels of androgen metabolites are lower in postmenopausal symptomatic menopausis than in matched controls and a significant decrease in conjugated dehydroepiandrosterone (DHEA) was found in the plasma of osteoporotic patients (Hollo and Feher, Acta Med. Hung. 20: 133, 1964; Urist and Vincent, J. Clin. Orthop. 18: 199, 1961; Hollo et al., Acta Med. Hung. 27: 155, 1970). It has been suggested that postmenopausal osteoporosis results from both hypoestrogenism and hypoandrogenism (Hollo et al., Lancet, 1357, 1976).
As a mechanism for the above-suggested role of both estrogens and androgens in osteoporosis, the presence of estrogen (Komm et al., Science 241: 81-84, 1988; Eriksen et al., Science 241: 84-86, 1988) as well as androgen (Colvard et al., Proc. Natl. Acad. Sci. 86: 854-857, 1989) receptors in osteoblasts could explain increased bone resorption observed after estrogen and androgen depletion.
While, in women, there is a rapid bone loss starting at menopause, bone loss in males can be recognized at about 65 years of age (Riggs et al., J. Clin. Invest. 67: 328-335, 1987). A more significant bone loss is seen in men at about 80 years of age, with the accompanying occurrence of hip, spine and wrist fractures. Several studies indicate that osteoporosis is a clinical manifestation of androgen deficiency in men (Baran et al., Calcif. Tissue Res. 26: 103-106, 1978; Odell and Swerdloff, West J. Med. 124: 446-475, 1976; Smith and Walker, Calif. Tissue Res. 22 (Suppl.): 225-228, 1976).
Therapy of postmenopausal women with nandrolone increased cortical bone mineral content (Clin. Orthop. 225: 273-277). Androgenic side-effects, however, were recorded in 50% of patients. Such data are of interest since while most therapies are limited to an arrest of bone loss, an increase in bone mass was found with the use of the anabolic steroid nandrolone. A similar stimulation of bone formation by androgens has been suggested in a hypogonadal male (Baran et al., Calcif. Tissue Res. 26: 103, 1978).
The decline with age of serum levels of DHEA-S and DHEA has led to the intriguing possibility that low serum DHEA and DHEA-S levels could be associated with cancer and cardiovascular diseases. In fact, a series of studies have indicated that subnormal levels of DHEA are associated with a high risk of breast cancer (Bulbrook et al., Lancet 2: 395-398, 1971; Rose et al., Eur. J. Cancer 13: 43-47, 1977; Thijssen et al., J. Steroid Biochem. 6: 729-734, 1975; Wang et al., Eur. J. Cancer 10: 477-482, 1974; Gomes et al., C. R. Acad. Sci. Paris 306: 261-264, 1978; Brownsez et al., Eur. J. Cancer 8: 131-137, 1972). Women with breast cancer were found to have low urinary levels of androsterone and etiocholanolone, two metabolites of DHEA (Bulbrook et al., Lancet 2:1238-1240, 1962; Cameron et al., Br. Med. J. 4: 768-771, 1970). Bulbrook et al. (Lancet 2: 1235-1240, 1962) then reported that women with primary operable breast cancer had urinary levels of 11-deoxy-17-ketosteroids (derived mainly from DHEA-S and DHEA) lower than normal, thus suggesting that a low secretion rate of DHEA and DHEA-S could precede the development of breast cancer.
The main approaches for the treatment of already developed breast cancer are related to the inhibition of estrogen action and/or formation. The role of estrogens in promoting the growth of estrogen-sensitive breast cancer has been recognized (Lippman, Semin. Oncol. 10 (Suppl. 4): 11-19, 1983; Sledge and McCuire, Cancer Res. 38: 61-75, 1984; Witliff, Cancer 53: 630-643, 1984; Poulin and Labrie, Cancer Res. 46: 4933-4937, 1986).
DHEA (450 mg/kg, b.w., 3 times a week) markedly delayed the appearance of breast tumors in C3H mice which were genetically bred to develop breast cancer (Schwartz, Cancer Res. 39: 1129-1132, 1979). Moreover, the risk of developing bladder cancer was found to be increased in men having lower serum DHEA levels (Gordon et al., Cancer Res. 51: 1366-1369, 1991).
Copending U.S. patent application Ser. No. 07/785,890 filed Nov. 4, 1991, relates to a method of treatment of breast and endometrial cancer in susceptible warm-blooded animals which may include inhibition of ovarian hormonal secretion by surgical means (ovariectomy) or chemical means (use of an LHRH agonist, e.g. D-Trp.sup.6, des-Gly-NH.sub.2.sup.10 !LHRH ethylamide, or antagonist) as part of a combination therapy. Antiestrogens, androgens, progestins, inhibitors of sex steroid formation (especially of 17.beta.-hydroxysteroid dehydrogenase- or aromatase-catalyzed production of sex steroids), inhibitors of prolactin secretion and of growth hormone secretion and ACTH secretion are discussed.
Copending U.S. patent application Ser. No. 07/724,532 filed on Jun. 28, 1991, relates to a method using low dose androgenic compounds for the prevention and treatment of breast cancer, endometrial cancer, osteoporosis and endometriosis.
Recent in vitro studies describe the relative antiproliferative activities of an androgen on the growth of the estrogen-sensitive human mammary carcinoma cell line ZR-75-1 (Poulin et al. "Androgens inhibit basal and estrogen-induced cell proliferation in the ZR-75-1 human breast cancer cell line", Breast Cancer Res. Treatm. 12: 213-225, 1989). As mentioned above, Poulin et al. (Breast Cancer Res. Treatm. 12: 213-225, 1989) have found that the growth of ZR-75-1 human breast carcinoma cells is inhibited by androgens, the inhibitory effect of androgens being additive to that of an antiestrogen. The inhibitory effect of androgens on the growth of human breast carcinoma cells ZR-75-1 has also been observed in vivo in nude mice (Dauvois and Labrie, Cancer Res. 51: 3131-3135, 1991).
DHEA has been suggested to have beneficial effects in obesity, diabetes, atherosclerosis, cancer, autoimmune diseases, fatigue, loss of muscle mass, connective tissue diseases, aging and longevity (Orentreich et al., J. Clin. Endocrinol. Metab. 59: 551-555, 1984; Regelson, Ann. N.Y. Acad. Sci. 521: 260-273, 1988; Gordon et al., Adv. Enzyme Regul. 26: 355-383, 1987; Schwartz, Adv. Cancer Res. 51: 391-423, 1988; Barrett-Connor et al., New Engl. J. Med. 315: 1519-1524, 1986).
In aged Sprague-Dawley rats, Schwartz (in Kent, Geriatrics 37: 157-160, 1982) has observed that body weight was reduced from 600 to 550 g by DHEA without affecting food intake. Schwartz (Cancer 39: 1129-1132, 1979) observed that C3H mice given DHEA (450 mg/kg, 3 times a week) gained significantly less weight and grew older than the control animals, had less body fat and were more active. The reduction in body weight was achieved without loss of appetite or food restriction. Furthermore, DHEA could prevent weight gain in animals bred to become obese in adulthood (in Kent, Geriatrics 37: 157-160, 1982).
DHEA in the diet has been shown to be a potent antihyperglycemic and antidiabetic agent in mice with inherited obesity-glucose intolerance syndrome (Coleman et al., Diabetes 33: 26-32, 1984).
DHEA reduced the incidence of atherosclerosis in cholesterol-fed rabbits (Gordon et al., J. Clin. Invest. 82: 712-720, 1988; Arad et al., Arteriosclerosis 9: 159-166, 1989). Moreover, high serum concentrations of DHEA-S have been reported to protect against death from cardiovascular diseases in men (Barrett-Connor et al., N. Encl. J. Med. 315: 1519-1524, 1986). Circulating levels of DHEA and DHEA-S have thus been found to be inversely correlated with mortality from cardiovascular disease (Barret-Connor et al., N. Engl. J. Med. 315: 1519-1524, 1986) and to decrease in parallel with the diminished immune competence (Thoman and Weigle, Adv. Immunol. 46: 221-222, 1989). A study in man has shown an inverse correlation between fetal serum DHEA-S and low density lipoprotein (LDL) levels (Parker et al., Science 208: 512, 1980).
In normal men, a placebo-controlled trial investigated the effect of daily oral administration of 1.6 g of DHEA for 28 days. Serum DHEA levels were increased 2.5- to 3.5-fold in the DHEA-treated group while total cholesterol and serum LDL cholesterol decreased by 7.1 and 7.5%, respectively (Nestler et al., J. Clin. Endocrinol. Metab. 66: 57-61, 1988). A decrease in body fat was found in 4 of the 5 men treated with DHEA for an average 31% decrease in percent of body fat with no change in total weight, thus suggesting a corresponding increase in muscle mass.
Drucker et al. (J. Clin. Endocrinol. Metab. 35, 48, 1972), Buster et al. (Am. J. Obstet. Gynecol. 166, 1163, 1992) and Welle et al. (J. Clin. Endocrinol. Metab., 71, 1259, 1990) have also administered DHEA orally to the human.
Obesity was found to be improved in the AvY mutant mouse (Yen et al., Lipids 12: 409-413, 1977) and in the Zucker rat (Cleary and Zisk, Fed. Proc. 42: 536, 1983). DHEA-treated C3H mice had a younger appearance than controls (Schwartz, Cancer Res. 39: 1129-1132, 1979).
Brain concentrations of DHEA are 6.5 times higher than corresponding concentrations in plasma (Lacroix et al., J. Steroid Biochem. 28: 317-325, 1987). DHEA and DHEA-S improve memory in aging mice (Flood and Roberts, Brain Res. 448: 178-181, 1988). Serum DHEA-S concentrations in patients with Alzheimer disease have been found to be 48% lower on average than in age-matched controls (Sunderland et al., Lancet ii: 570, 1989). As mentioned above, DHEA administered chronically in the diet has been shown to increase longevity by delaying the development of some diseases in particular strains of animals.
U.S. Pat. No 4,496,556 describes the use of DHEA or its derivatives to treat skin dryness by topical administration. Only local action on the sebaceous glands was described and no systemic action was observed.
U.S. Pat. No 4,542,129 describes a topical composition for treating dry skin in a patient comprising the combination of DHEA and/or derivatives, a keratolytic agent and a non-toxic dermatologically acceptable vehicle.
Great Britain Patent No 1246639 describes preparation of esters of dehydroepiandrosterone for use as agents in the treatment of post and premenopause, tachycardia and headaches.
One problem facing the use of DHEA in humans is that high doses are required apparently because a large proportion of the compound is degraded in the liver before it reaches the blood stream after oral administration.
It is known that the efficiency of delivery of some drug can be improved by the use of certain pharmacologically inactive derivatives which are, by in vivo enzymatic or spontaneous reactions, transformed into the active drugs (see generally H. Bundgaard, Design and application of prodrugs. In A textbook of Drug Design and Development. Edited by P. Krogsgaard-Larsen and H. Bundgaard. Harwood Academic Publishers GmfH, Chur, Switzerland, 1991, pp. 113-191). For example, Druzgala et al., J. Steroid Biochem. Molec. Biol. 38, 149-154, 1991, describes prodrugs of glucocorticoids. Bodor et al. in U.S. patent Application Ser. No. 4,213,978 and in German Patent Application Publication No DE 29 48 733 disclose the use of thiazolidine derivatives of progesterone as topical drugs. Percutaneous absorption of prodrug derivatives of estrogens and progestins are reported by Friend DR in Critical Reviews in Therapeutic Drug Carrier Systems, vol. 7 (2), pp. 149-186, 1990. Information about percutaneous absorption of drugs can also be found in Skin Permeability (H. Schaefer, A. Zesch and G. Stuttgen, eds), Springer-Verlag, Berlin, Heidelberg, New York, 1982, pp. 896.
Currently, low dose estrogen therapy is the standard approach used in perimenopausal and menopausal women to relieve vasomotor symptoms, urogenital atrophy, osteoporosis and other symptoms and signs associated with menopause (for review, see Edman, C. D., Estrogen Replacement Therapy. In: The menopause, Springer-Verlag, New York, (edited by H. J. Buchsbaum), pp. 77-84, 1983). Detailed information about the menopause and its therapy can be found in other chapters of this book. Obviously, such approaches limited to estrogen replacement therapy, associated or not with progestins, do not reproduce the equilibrium between estrogens and androgens that occurs naturally from the transformation of DHEA into its active metabolites in various target tissues.
Some esters of DHEA at position 3 are already described in the litterature (Riva et al., J. Org. Chem. 54: 3161-4, 1989; Parish and Chistrakorn, Synth. Commun. 15: 393-9, 1985; Rom Patent No RO 66924B; Jarosz and Zamojski, Tetrahedron 38:1453-6, 1982; Heublin et al., Z. Chem. 22: 178, 1982; German Patent Application No DE 2534911; Khaidem et al., Indian J. Chem. Sect. B, 27B: 850-1, 1988; Pettit et al., J. Org. Chem. 52: 3573-8, 1987; Hanson and Reese, J. Chem. Soc. Perkin Trans. 1: 647-649, 1985); European Patent Application No 84-105741; Heublein et al., Acta Polym., 35: 673-7, 1984; Seevers et al., J. Med. Chem., 25: 1500-3, 1982; Yamashita and Kurosawa, Agric. Biol. Chem., 39: 2243-4, 1975; Japan Patent Application JP 50005372; Pohlmann et al., Mol. Cryst. Liquid Cryst. 13: 243-54,1971.
Alkanesulfonates of DHEA is described as inhibitors of glucose-6-phosphate dehydrogenase activity in J. Pharm. Sci. 73: 1643-5, 1984.
In Britain Patent Application No GB 1246639 and S. Africa Patent Application No ZA 6806112 is disclosed DHEA esters for the treatment respectively of post and premenopause tachycardia and headaches and climateric complaints.
Leszczynski et al., in Biochem. Biophys. Acta, 1014: 90-7, 1989; idem: 1083: 18-28, 1991, have reported esterification of DHEA by blood plasma and Katz et al., in MCF-7 cell line in J. Steroid Biochem, 26: 687-92, 1987.
Ethyl carbonate of DHEA is reported by Weisz and Agocs in Arch. Pharm. (Weinheim, Ger), 319: 952-3, 1986.
Some halogeno esters of DHEA are described by Challis and Heap in J. Chromatogr. 50: 228-238, 1970 and by Pinelly and Nair in J. Chromatogr. 43: 223-228, 1969.